the former Honeywell plant building (3 Hamilton Avenue) a single-storey brick industrial/commercial building (233 Armstrong Street)

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1 consulting engineers memorandum to: Tega Developments - Mr. Spyro Dimitrakopoulos - spyro@tegadevelopments.com re: Environmental Remedial Action Plan Proposed Residential Building 233 Armstrong Street and 3 Hamilton Avenue - Ottawa date: December 20, 2012 file: from: PE2183-MEMO.14R Carlos P. Da Silva, P.Eng. Further to your request, Paterson Group (Paterson) have revised the previous remedial action plan (RAP) for the aforementioned site based on recently available information. Proposed Development The proposed development will consist of two multi-storey buildings with 6 levels of underground parking. The parking garage footprint will occupy the entire boundary of the 2 subject site (an area of approximately 3,000 m ). The proposed founding depth is expected at approximately 21 m below the existing grade within the bedrock and will be below the long term groundwater depth (approximately 4 m below the existing grade). Background The subject site is currently impacted with chlorinated solvents (VOCs) associated with the operation of the former Honeywell manufacturing plant which disposed of the contaminants of concerns within a dry well located within the courtyard at 3 Hamilton Avenue. Contaminants of concern (COC) include tetrachloroethylene or perchloroethylene (PCE), trichloroethylene (TCE), dichloroethylene (DCE), and vinyl chloride (VC). Detailed environmental characterization of on-site and off-site impacts has been previously completed by others and supplemented by Paterson. The subject site is currently occupied by two buildings: the former Honeywell plant building (3 Hamilton Avenue) a single-storey brick industrial/commercial building (233 Armstrong Street) A third building, the Carleton Tavern, is present in the same city block as the subject site, however, is not part of the subject property. Bedrock at the site is shallow, and impacts to overburden soils are expected to be limited due to a partial soil remediation program previously completed by Honeywell.

2 Page 2 To address the on-site groundwater impacts, a pump-and-treat system was implemented by Golder Associates (Honeywell s environmental consultant). This system has been operating since January VOC levels have been decreasing slowly, though they remain well above 2004 and 2009 MOE standards. However, the presence of DCE and VC, daughter products of PCE and TCE, suggests that the release of product is historical and that natural attenuation with biodegradation of contaminants is occurring. A cross sectional drawing of the impacted zone was produced by Golder and indicates a significantly impacted plume between 6 and 12 m below the existing grade. The highly impacted plume also extends beneath the Carleton Tavern and off-site. Deep Monitoring Well Installation Program In November and December 2012, Paterson completed a deep borehole drilling and groundwater sampling program at the subject site to determine groundwater quality at the depth interval of approximately 21 to 23 m. The purpose of the deep well was to confirm if a generic approach could be considered for the suggested remedial program. To prevent vertical migration from upper contaminated intervals, the borehole (BH1-12) was drilled to 11.9 m using PQ-diameter drill rods, which were then grouted in place with a cementbased grout. HQ-diameter drill rods were then advanced through the grout and underlying bedrock to a depth of 20.8 m and grouted in place. Finally, NQ-diameter drill rods were advanced through the grout and underlying bedrock, leaving an open hole interval from 20.8 to 22.9 m. Following drilling, BH1-12 was purged dry to remove water introduced into the borehole during the coring process. Two groundwater samples were recovered from the open hole using dedicated polyethylene sampling tubing and analyzed for volatile organic compounds (VOCs). Selected laboratory results are summarized in Table 1, below. All other parameters are below laboratory detection limits. Concentrations of chlorinated solvent parameters (PCE, TCE, DCE, and VC) were non-detect based on laboratory detection limits. All other detected parameters were in compliance with MOE Table 3 standards, with the exception of chloroform. The presence of chloroform is inferred to be a result of the use of municipally-treated water as core water. The decreasing concentrations of chloroform suggest that the core water is gradually being removed from the rock formation. Based on the results of the deep borehole drilling and groundwater sampling program, in our opinion, the chlorinated solvents detected in the groundwater in the upper bedrock at the site have not penetrated to the 21 to 23 m depth interval in the central portion of the site.

3 Page 3 Table 1 Selected Analytical Test Results - Groundwater at m Depth Volatile Organic Compounds (VOCs) Parameter MDL (ìg/l) Groundwater Sample (ìg/l) 2011 Table 3 BH1-12-GW1 December 7, 2012 BH1-12-GW2 December 14, 2012 Standards (ìg/l) Acetone ,000 Bromodichloromethane nd 85,000 Chloroform ,1-Dichloroethylene 0.5 nd nd 1.6 cis-1,2-dichloroethylene 0.5 nd nd 1.6 trans-1,2-dichloroethylene 0.5 nd nd 1.6 Methyl Ethyl Ketone 5.0 nd ,000 Tetrachloroethylene 0.5 nd nd 1.6 Trichloroethylene 0.4 nd nd 1.6 Toluene 0.5 nd ,000 Vinyl Chloride 0.4 nd nd 0.5 Notes: MDL - Method Detection Limit nd - not detected above the MDL N/V - no value provided by the MOE ( ) Standard value in brackets applies to medium and fine textured soils Bold - Value exceeds MOE Table 3 Standard Environmental Rationale The environmental rationale for implementing the suggested remedial action plan is as follows: To develop the subject site, a Record of Site Condition (RSC) is required by the City of Ottawa due to a land use change. The RSC can only be obtained once the soil and groundwater is in compliance with applicable MOE standards. A generic approach remediation program will be possible to achieve this. A remediation program using a full depth approach will allow for a deep excavation for 6 levels of underground parking into the bedrock to extend below the chlorinated solvent impacted groundwater depth of approximately 18 m.

4 Page 4 Since the excavation program will be located within the contamination source area, all impacted soil and potentially impacted bedrock will be removed and disposed off-site at an approved waste disposal facility. Source removal will be the key component of the overall remediation program. A successful remedial program is contingent on source removal. The depth of the excavation will be effective in removing the all the impacted groundwater. The results of the recent deep well investigation indicate that contamination is not present at a depth of 21 m below the existing grade in the central portion of the source area. Two additional deep monitoring wells will be required to confirm groundwater quality and satisfy RSC requirements. It is expected that the excavation will remain open for a period of 8 to 12 months until the footings and foundation walls are completed. The deep excavation will act as a sink hole creating a draw down of the groundwater from the surrounding area. It is expected that a radius of influence from the groundwater lowering effect will range from approximately 3H:1V to 5H:1V within the fractured bedrock at a depth of 21 m below the existing grade. With an expected 17 m draw down of the long term groundwater level (21 m depth of excavation less 4 m long term groundwater level), it is expected that a radius of influence of 85 to 170 m will be created at the groundwater surface surrounding the subject site. At the depth of highest impacts, the zone of influence will be approximately 40 to 80 m depending on the fractured nature of the bedrock at the depth of 8 to 12 m. Off-site impacted groundwater in proximity to the excavation will be re-directed to the excavation. All water infiltration will be immediately collected in the lower portion of the excavation and will be pumped through a treatment system prior to disposal. Any VOC impacted groundwater remaining off site will be the responsibility of Honeywell and their environmental consultant which have off-site indemnification agreements in place. It is expected that an area wide risk assessment may be undertaken by Honeywell for all off-site and any residual impacted groundwater surrounding the site including the right-of-way and any other affected areas. The area wide risk assessment will have the greatest potential for acceptance by the MOE once the source removal is completed along with a proactive and aggressive approach to impacted groundwater recovery and treatment. A successful remedial action plan will require the cooperation of several involved parties.

5 Page 5 Remedial Action Plan Summary The proposed residential development will require a Record of Site Condition (RSC). To meet the conditions of a RSC, the suggested remedial action plan is as follows: Two additional deep monitoring wells be drilled using the same methodology as the recently installed monitoring well to confirm that groundwater contamination is not present below the proposed founding depth of 21 m. A remediation program using a full depth generic approach will be used. This will involve the source removal by excavating all VOC impacted soil, bedrock, and groundwater from within the boundaries of the subject site. Existing buildings on-site will be demolished as part of the re-development of the site. Overburden soils, where present, will be stripped and segregated for off site disposal. 3 Soil will be stockpiled in 20 to 40 m piles, environmentally screened and tested for VOC impacts. Any VOC impacted soil encountered will be disposed at an approved waste disposal facility. Bedrock will be removed by means of line drilling and blasting. Line drilled holes along the site perimeter will be grouted immediately after drilling to eliminate potential vertical migration of COCs. Excavated soil and bedrock will be screened using visual and olfactory observations and a portable soil vapour analyser. Impacted soil and bedrock will be placed in trucks and hauled to an approved waste disposal facility. Non-impacted soil and bedrock will be placed in trucks and hauled off-site for possible re-use or disposal as clean material. Once the excavation is completed, the bedrock face of the excavation will be sprayed with a 50 mm layer of shotcrete to satisfy Honeywell s request. The purpose of the shotcrete will be to seal the bedrock surface to lessen the effects of vertical migration of the off-site impacted groundwater. Groundwater and surface water infiltration entering the excavation will be immediately directed into a lowered area of the excavation. The water will them be pumped through a treatment system prior to disposal to the appropriate sewer based on treatment levels complying with the applicable Ottawa Sewer Use By-law standards and discharged into the sanitary or storm sewer. VOCs will be treated by means of air stripping and/or granular activated carbon (GAC). It is expected that the groundwater treatment will be in place until the parking garage is completed and when sufficient load is being applied to the concrete raft slab to resist hydrostatic lift.

6 Page 6 A pressure relief chamber will be constructed once the excavation is complete and will be used to capture and direct water for treatment. Once the foundation has been poured and completed, the relief valve will be closed and hydrostatic pressure will then be allowed to build up. A permit to take water (PTTW) from the Ontario Ministry of the Environment (MOE) will be required and will be obtained prior to commencing the pumping operations. As part of the floor slab waterproofing system and resistance to hydraulic up-lift, a concrete floor slab, anchored to the bedrock, will be poured at the final bedrock excavation depth. Rock anchors will be drilled and grouted at the base of the excavation in a pre-determined grid pattern. A VOC resistant membrane will be sandwiched between two layer of concrete and will act as the waterproofing medium. The waterproofing membrane will consist of VOC-resistant material. A similar waterproofing membrane will also be applied to the bedrock face and the vertical foundation walls. The waterproofing membrane will consist of VOC-resistant material and will be placed against the shotcrete layer. A composite drainage blanket will be added to intercept any groundwater that breaches the waterproofing membrane layer. The foundation walls will be designed to resist hydrostatic pressure. The foundation wall will be blind poured against the composite drainage system. Once the waterproofing system is completed and the basement levels are completed, the waterproofing system will be tested to ensure its effectiveness. Any potential leaks will be corrected. Once the effectiveness of the waterproofing system has been approved, a gravel layer will be placed between the rock anchored concrete raft slab and the finished floor slab. The gravel layer will be used to direct any water infiltration, due to a possible future breach of the waterproofing membrane, to a collection sump pit. Any collected water, if any, will then be pumped through a treatment system and discharged to the sanitary sewer. It is expected that the volume of potential future water infiltration will be very minimal due to the waterproofed system in place. A confirmatory sampling program will be carried out following the implementation of the remediation program outlined above. A summary report and a risk assessment based Record of Site Condition (RSC) will be submitted to MOE for acknowledgement.

7 Page 7 We trust that this information satisfies your requirements. Best Regards, Paterson Group Inc. Carlos P. Da Silva, P.Eng. Paterson Group Inc. Head Office and Laboratory Northern Office and Laboratory St. Lawrence Office 154 Colonnade Road South 63 Gibson Street 993 Princess Street - Suite 102 Ottawa - Ontario - K2E 7J5 North Bay - Ontario - P1B 8Z4 Kingston - Ontario - K7L 1H3 Tel: (613) Fax: (613) Tel: (705) Fax: (705) Tel: (613) Fax: (613)

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